Filter funnel base



FIG. 1 is a perspective view of a filter funnel base embodying our new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a side elevational view thereof; the opposite side view being a mirror image thereof; and,

FIG. 4 is a bottom plan view thereof. 

The ornamental design for a filter funnel base, as shown and described. 